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Building a patrol rifle? Beware the ‘Frankengun’

For many hobbyists and some departments, these parts are sourced based on their price or appearance instead of how well they function as a unit


In this July 20, 2012, file photo, a row of different AR-15 style rifles are displayed for sale at the Firing-Line indoor range and gun shop in Aurora, Colo.

AP Photo/Alex Brandon, File

One of the greatest things about the AR-15 is the rifle’s ability to adapt and change. A different buttstock, a new pistol grip, different handguards, a new lower receiver, a fancy new trigger and maybe a low-mass bolt carrier can make monstrous changes to your rifle. All of this can be done relatively inexpensively, in less than an hour and has been source of enjoyment for countless enthusiasts and competition shooters. However, if this is a patrol rifle meant to protect your life or the lives of others, beware of using the Franken-gun.

There are many people out there who have made a hobby out of building ARs, and many of these rifles are a lot of fun to shoot. I am one of those guys. I’ve been an AR-armorer for nearly 20 years, and I’ve built quite a few AR rifles – more than some folks and less than others. I’m confident the rifles I build and the parts I choose are going to work. However, I’ve tried some part combinations that didn’t work well, while other combinations seemed to work well only to fail sooner than expected. Sometimes it’s just a matter of whether or not the parts work in harmony. Like a band, one instrument may play, and another instrument may play, but it doesn’t mean they go together to make music. This has taught me that there is a difference between the rifles I use at work and the ones I build for competition, recreation and training.

Build it yourself?

I define a “Frankengun” as being a rifle built by a department armorer or individual hobbyist using parts that are purchased from a variety of sources. For example, a lower from one manufacturer paired with an upper from another manufacturer. Add a bolt carrier group assembled with parts from multiple manufacturers and you have yourself a Frankengun. Sights, optics, slings, lights and these types of accoutrements are not relevant to defining a Frankengun.

For many hobbyists and some departments, these parts are sourced based on their price or appearance instead of how well they function as a unit. This is the heart of the problem. Little to no testing goes into the research and development of the Franken-gun. At best, most Franken-guns are function tested then put into service. If more extensive testing is done, it generally means less than 500 rounds. This failure to exercise due diligence is dangerous for the officer and the community.

Recently, a firearms instructor from a respected agency in the Pacific Northwest told me that in order to get more rifles on the street, his agency had three different armorers building ARs to issue to their officers. This agency was buying parts and building rifles in house to save money. None of the armorers had built more than a dozen rifles, and the parts were selected with cost being the primary purchasing factor. The result has been predictable. Even though most of the rifles ran fine during qualifications, there were numerous problems with those weapons on the range during training. The difference was the department’s qualification consisted mostly of slow, deliberate shots while training included combat speed drills that built up significantly more heat, which increased the wear and stress on the cheap parts.

Another instructor from a similar sized agency in New Hampshire shared his experience of being issued a Frankengun only to have it fail during qualifications. Upon inspection, the carrier key was secured with only one un-staked screw, and the firing pin retaining pin had not been installed. It turned out, the department armorer who built his rifle had just recently attended an armorer class and was being allowed to piece together rifles to be issued to patrol officers. So, that agency has compounded the problems with Franken-guns by adding poor training and supervision of department armorers.

Factory patrol rifles

Admittedly, even rifles from well-known and respected manufacturers can have problems. However, these companies depend on the reliability and dependability of their products to stay in business; therefore, they tend to have very few overall problems. Since the future of their business hinges on their reputation, their rifles undergo significant research, development and testing before landing in the rack of your patrol car. In addition, the alloys used in the manufacturing process, the coatings used to protect the metal and reduce friction, and the design of each part is tested to ensure function and interoperability.

Factory rifles from respected manufacturers are subjected to thousands and thousands of rounds during testing and development to confirm their product is performing up to their standards. Once the factory is confident in their product, the rifles hit the shelves where consumers pick them up and put them through their own testing process. This results in thousands of people confirming the reliability and dependability of a factory rifle set up.

Additionally, for these skilled employees, putting rifles together is their primary responsibility. It is what they do for a living every day. They know these rifles and the parts used better than even the most skilled department armorer. Since these craftsman do this every day, they are much more likely to recognize potential problems than a department armorer. Look at it this way: these skilled craftsman know how to build a rifle, and we know how to utilize those same rifles to save lives.

Cost saving is another reason given by many departments and individual officers who build their own patrol rifles. In order to build a standard M4-type AR-15 for duty use, parts will run $400 to $600 depending on what is selected. Add in the expense of build time and that rifle will cost a department $600 to $800. This same rifle purchased at individual officer prices from a reputable manufacturer costs $550 to $750 and generally less for department price. Unless a department or individual officer is willing to pay top dollar for high end parts from high end suppliers, cost is not an issue when it comes to building a rifle for patrol use.

I’m not saying that all Frankenguns are junk. As a matter of fact, many end up being just as dependable and reliable as factory rifles. Building your own AR is educational and a lot of fun. It can provide a sense of satisfaction and a feeling of accomplishment after having built it with your own hands. It gives you a chance to pick and choose exactly how you want to set up your rifle. So, go ahead and build your AR for training, competition and recreation.

But, your patrol rifle is something your life may depend on. Having a factory rifle from a well-known and respected manufacturer ensures a professionally built rifle. A professionally built rifle has a history of research and development, extensive testing to confirm dependability and a reduced chance of builder errors. The question we should ask is whether professional crime fighters should put their lives and the lives of loved ones on a Frankengun built in a hobby shop.

Todd Fletcher is the owner and lead instructor for Combative Firearms Training, LLC providing training for law enforcement firearms instructors from coast to coast. He has over 25 years of training experience as a firearms and defensive tactics instructor. He retired after more than 25 years as a full-time police officer and over 31 years of law enforcement experience.

Todd is a member of the International Defensive Pistol Association (IDPA) and the United States Practical Shooting Association (USPSA). He is a member of the International Law Enforcement Educators and Trainers Association (ILEETA), and was selected as the 2022 ILEETA Trainer-of-the-Year. He is also a member of the International Association of Law Enforcement Firearms Instructors (IALEFI) and won the 2023 IALEFI Top Gun Award. He can be reached at